Method of manufacturing vertical semiconductor device

ABSTRACT

A vertical semiconductor device, a DRAM device, and associated methods, the vertical semiconductor device including single crystalline active bodies vertically disposed on an upper surface of a single crystalline substrate, each of the single crystalline active bodies having a first active portion on the substrate and a second active portion on the first active portion, and the first active portion having a first width smaller than a second width of the second active portion, a gate insulating layer on a sidewall of the first active portion and the upper surface of the substrate, a gate electrode on the gate insulating layer, the gate electrode having a linear shape surrounding the active bodies, a first impurity region in the upper surface of the substrate under the active bodies, and a second impurity region in the second active portion.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional application based on application Ser. No.12/585,776, filed Sep. 24, 2009 now abandoned, the entire contents ofwhich is hereby incorporated by reference.

BACKGROUND

1. Field

Embodiments relate to a vertical semiconductor device, a DRAM deviceincluding the same, and associated methods.

2. Description of the Related Art

As semiconductor devices have become highly integrated, a gate length ofa MOS transistor in the semiconductor device may gradually decrease.Thus, it may be desirable that the MOS transistor have athree-dimensional structure.

For example, in order to increase an integration degree of asemiconductor device, cell transistors of a unit chip may includevertical pillar transistors having a channel direction extendingsubstantially vertically from an upper surface of a semiconductorsubstrate. The vertical pillar transistor may have a relatively smallerhorizontal area and a relatively longer channel length when compared tothose of a planar transistor. However, because the vertical pillartransistor may require complicated manufacturing processes, it may bedifficult to produce the vertical pillar transistors on a large scale.

The vertical pillar transistor may include a gate on a sidewall of avertical semiconductor pillar. Thus, the vertical pillar transistor mayhave variable characteristics in accordance with the verticalsemiconductor pillar. In order to improve operational characteristics ofthe vertical pillar transistor, it may be desirable to form a verticalsemiconductor pillar having good charge conduction characteristicswithout defects.

SUMMARY

Embodiments are directed to a vertical semiconductor device, a DRAMdevice including the same, and associated methods, which substantiallyovercome one or more of the drawbacks, limitations, and/or disadvantagesof the related art.

It is a feature of an embodiment to provide a vertical semiconductordevice having good channel characteristics.

It is another feature of an embodiment to provide a method ofmanufacturing a vertical semiconductor device by simple processes.

At least one of the above and other features and advantages may berealized by providing a vertical semiconductor device including singlecrystalline active bodies vertically disposed on an upper surface of asingle crystalline substrate, each of the single crystalline activebodies having a first active portion on the substrate and a secondactive portion on the first active portion, and the first active portionhaving a first width smaller than a second width of the second activeportion, a gate insulating layer on a sidewall of the first activeportion and the upper surface of the substrate, a gate electrode on thegate insulating layer, the gate electrode having a linear shapesurrounding the active bodies, a first impurity region in the uppersurface of the substrate under the active bodies, and a second impurityregion in the second active portion.

The active bodies may be formed by a laser epitaxial process.

The first width may be about 5 nm to about 30 nm.

At least one of the above and other features and advantages may also berealized by providing a method of manufacturing a vertical semiconductordevice including implanting impurities into a single crystallinesubstrate to form a first impurity region, forming a sacrificial layerstructure on an upper surface of the substrate, such that thesacrificial layer structure has holes exposing the first impurity regionon the upper surface of the single-crystalline substrate, forming innerspacers on side surfaces of the holes, vertically forming singlecrystalline active bodies in the holes on the upper surface of thesingle crystalline substrate, such that each of the single crystallineactive bodies has a first active portion on the substrate and a secondactive portion on the first active portion and such that the firstactive portion has a first width smaller than a second width of thesecond active portion, forming a gate insulating layer on a sidewall ofthe first active portion and the upper surface of the substrate, forminga gate electrode on the gate insulating layer, such that the gateelectrode has a linear shape surrounding the active bodies, andimplanting impurities into the second active portion to form a secondimpurity region.

Forming the sacrificial layer structure may include forming asacrificial layer on the substrate, forming a first protecting layer onthe sacrificial layer, and etching the sacrificial layer and the firstprotecting layer to form the sacrificial layer structure having theholes.

Forming the sacrificial layer may include forming a pad oxide layer onthe substrate, forming a silicon nitride layer on the pad oxide layer,and forming a silicon oxide layer on the silicon nitride layer.

The method may further include forming a second protecting layer on thesacrificial layer structure to cover the active bodies.

The method may further include patterning the sacrificial layerstructure to expose the sacrificial layer, and removing the sacrificiallayer and inner spacers to expose the sidewall of the first activeportion.

The gate insulating layer may be formed on the exposed sidewall of thefirst active portion.

The inner spacer may have an upper surface lower than that of thesacrificial layer structure.

A distance between the upper surface of the inner spacer and the uppersurface of the sacrificial layer structure may be substantially the sameas a length of the second active portion.

A width between the inner spacers in the hole may be about 5 nm to about30 nm.

Forming the active bodies may include filling an opening between theinner spacers with a polysilicon layer pattern, and thermally treatingthe polysilicon layer pattern using a laser to form the active bodies.

Forming the gate insulating layer and the gate electrode may includeoxidizing surfaces of the first active portion and the substrate to formthe gate insulating layer, forming a conductive layer on the substrateto cover the gate insulating layer, and patterning the conductive layerto form the linear gate electrode.

At least one of the above and other features and advantages may also berealized by providing a DRAM device including single crystalline activebodies vertically disposed on an upper surface of a single crystallinesubstrate, each of the single crystalline active bodies having a firstactive portion on the substrate and a second active portion on the firstactive portion, and the first active portion having a first widthsmaller than a second width of the second active portion, a gateinsulating layer on a sidewall of the first active portion and the uppersurface of the substrate, a gate electrode on the gate insulating layer,the gate electrode having a linear shape surrounding the active bodies,and the gate electrode being usable with a word line, a first impurityregion in the upper surface of the substrate under the active bodies, asecond impurity region in the second active portion, a bit linestructure electrically connected to the first impurity region, and acapacitor electrically connected to the second impurity region.

The first width may be about 5 nm to about 30 nm.

The substrate may have an isolation region and an active region, and theactive region may have an extending direction at an angle of no morethan about 90° with respect to the gate electrode.

The DRAM may further include a protecting layer covering an uppersurface and an upper sidewall of the active bodies.

At least one of the above and other features and advantages may also berealized by providing a method of manufacturing a DRAM device includingimplanting impurities in an upper surface of a single crystallinesubstrate to form a first impurity region, forming a sacrificial layerstructure on an upper surface of the substrate, such that thesacrificial layer structure has holes exposing the first impurity regionin the upper surface of the single-crystalline substrate, forming innerspacers on side surfaces of the holes, vertically forming singlecrystalline active bodies on the upper surface of the single crystallinesubstrate, such that each of the single crystalline active bodies has afirst active portion on the substrate and a second active portion on thefirst active portion and such that the first active portion has a firstwidth smaller than a second width of the second active portion, forminga gate insulating layer on a sidewall of the first active portion andthe upper surface of the substrate, forming a gate electrode on the gateinsulating layer, such that the gate electrode has a linear shapesurrounding the active bodies, implanting impurities into the secondactive portion to form a second impurity region, electrically connectinga bit line structure to the first impurity region, and electricallyconnecting a capacitor to the second impurity region.

Forming the active bodies may include filling an opening between theinner spacers with a polysilicon layer pattern, and thermally treatingthe polysilicon layer pattern using a laser to form the active bodies.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages will become more apparent tothose of ordinary skill in the art by describing in detail exemplaryembodiments with reference to the attached drawings, in which:

FIG. 1 illustrates a cross-sectional view of a vertical transistor inaccordance with an embodiment;

FIG. 2 illustrates a perspective view of the vertical transistor of FIG.1;

FIG. 3 illustrates a perspective view of a single crystalline epitaxiallayer pattern of the vertical transistor of FIG. 1;

FIGS. 4 to 13 illustrate cross-sectional views of stages in a method ofmanufacturing the vertical transistor of FIG. 1;

FIG. 14 illustrates a cross-sectional view of a DRAM device includingthe vertical transistor of FIG. 1;

FIG. 15 illustrates a plan view of a DRAM device including the verticaltransistor of FIG. 1;

FIGS. 16 to 20 illustrate cross-sectional views of stages in a method ofmanufacturing the DRAM device of FIG. 14;

FIG. 21 illustrates a block diagram of a memory system in accordancewith an embodiment;

FIG. 22 illustrates a block diagram of a host system in accordance withan embodiment;

FIG. 23 illustrates a block diagram of a portable device in accordancewith an embodiment; and

FIG. 24 illustrates a block diagram of a computer system in accordancewith an embodiment.

DETAILED DESCRIPTION

Korean Patent Application No. 10-2008-0094800, filed on Sep. 26, 2008,in the Korean Intellectual Property Office, and entitled: “VerticalSemiconductor Device and Method of Manufacturing the Same,” isincorporated by reference herein in its entirety.

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout.

It will be understood that when an element or layer is referred to asbeing “connected to” or “coupled to” another element or layer, it can bedirectly connected or coupled to the other element or layer orintervening elements or layers may be present. In contrast, when anelement is referred to as being “directly connected to” or “directlycoupled to” another element or layer, there are no intervening elementsor layers present. Like numerals refer to like elements throughout. Asused herein, the term “and/or” includes any and all combinations of oneor more of the associated listed items.

It will be understood that, although the terms first, second, third etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the present invention.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of thepresent invention. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will, typically, have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature and their shapes are not intended to illustrate the actualshape of a region of a device and are not intended to limit the scope ofthe present invention.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Hereinafter, embodiments will be explained in detail with reference tothe accompanying drawings.

Vertical Transistor

FIG. 1 illustrates a cross-sectional view of a vertical transistor inaccordance with an embodiment. FIG. 2 illustrates a perspective view ofthe vertical transistor of FIG. 1. FIG. 3 illustrates a perspective viewof a single crystalline epitaxial layer pattern of the verticaltransistor of FIG. 1.

Referring to FIGS. 1 to 3, a single crystalline epitaxial layer pattern32 may contact an upper surface of a single crystalline semiconductorsubstrate 10. The epitaxial layer pattern 32 may have, e.g., a pillarshape. That is, the epitaxial layer pattern 32 may have a shapevertically extending from the upper surface of the semiconductorsubstrate 10. The epitaxial layer pattern 32 may serve as an activebody.

The epitaxial layer pattern 32 may have a first active portion 32 a anda second active portion 32 b on the first active portion 32 a. The firstactive portion 32 a may serve as a channel region of the verticaltransistor. The second active portion 32 b may serve as a contact plug.Thus, hereinafter, the first active portion 32 a may be referred to as achannel portion and the second active portion 32 b may be referred to asa contact portion.

The channel portion 32 a may have a width of about 5 nm to about 30 nm.Preferably, the width is about 10 nm. Thus, the channel portion 32 a mayhave a nano-wire structure. Such a structure may enable a desirablevolume inversion in the channel region of the vertical transistor.

The contact portion 32 b may have a width greater than that of thechannel portion 32 a. Accordingly, the contact portion 32 b may have anupper surface on which a contact plug may be easily formed.

An intersection portion between the channel portion 32 a and the contactportion 32 b may have a gradually decreased width in a downwarddirection. The width of the channel portion 32 a may allow the volumeinversion. The channel portion 32 a may have a lower surface thatcontacts the upper surface of the semiconductor substrate 10. The singlecrystalline epitaxial layer pattern 32 may be formed by, e.g., a laserepitaxial process.

A gate insulating layer 38 may be formed on a sidewall of the channelportion 32 a and the upper surface of the semiconductor substrate 10.The gate insulating layer 38 may include, e.g., silicon oxide formed bya thermal oxidation process.

A gate electrode 40 a may be formed on the gate insulating layer 38 tosurround the single crystalline epitaxial layer pattern 32. The gateelectrode 40 a may have a linear shape surrounding adjacent singlecrystalline epitaxial layer patterns 32. The gate electrode 40 a mayhave an upper surface lower than an upper surface of the singlecrystalline epitaxial layer pattern 32. Therefore, because the gateelectrode 40 a may surround the single crystalline epitaxial layerpattern 32, and the channel portion 32 a of the epitaxial layer pattern32 may be a nano-wire, the channel region may be formed both inside theepitaxial layer pattern 32 as well as on a surface of the epitaxiallayer pattern 32.

A first impurity region 12 may be formed in the upper surface of thesemiconductor substrate 10 under the single crystalline epitaxial layerpattern 32. A second impurity region 42 may be formed in the contactportion 32 b of the epitaxial layer pattern 32.

A protecting layer pattern 35 may be formed on a side upper surface andthe upper surface of the epitaxial layer pattern 32. The protectinglayer pattern 35 may include a first protecting layer 20 on the sideupper surface of the epitaxial layer pattern 32 and a second protectinglayer 34 on the upper surface of the epitaxial layer pattern 32. Theprotecting layer pattern 35 may have a linear shape extending in adirection substantially in parallel with that of the gate electrode 40a. A pad oxide layer 14 and a silicon nitride layer 16 may besequentially formed on the semiconductor substrate 10 between the gateelectrodes 40 a of the vertical transistors.

According to an embodiment, the channel region of the verticalsemiconductor device may be formed as a nano-wire in the singlecrystalline epitaxial layer pattern. Thus, the channel region may beformed by volume inversion, not surface inversion, during operation ofthe vertical transistor. Accordingly, the vertical semiconductor devicemay have good conductivity in the channel region and thus an increasedcurrent passing through the channel region. As a result, the verticalsemiconductor device may have improved operational characteristics.

Method of Manufacturing a Vertical Transistor

FIGS. 4 to 13 illustrate cross-sectional views of stages in a method ofmanufacturing the vertical transistor in FIG. 1. Referring to FIG. 4,impurities may be implanted into a single crystalline semiconductorsubstrate 10 to form a first impurity region 12. The first impurityregion 12 may be used as any one of a source region and a drain regionof the vertical transistor.

A sacrificial layer structure 22 may be formed on the semiconductorsubstrate 10. The sacrificial layer may be formed by the followingsteps. A pad oxide layer 14 may be formed on the semiconductor substrate10. A silicon nitride layer 16 may be formed on the pad oxide layer 14.The pad oxide layer 14 interposed between the silicon nitride layer 16and the semiconductor substrate 10 may reduce stresses between thesilicon nitride layer 16 and the semiconductor substrate 10. A siliconoxide layer 18 may then be formed on the silicon nitride layer 16. Thesilicon oxide layer 18 may have an upper surface substantially alignedwith an end of a channel portion in a single crystalline epitaxial layerpattern to be formed later, as described below. A first protecting layer20 may then be formed on the silicon oxide layer 18. The firstprotecting layer 20 may include, e.g., silicon nitride. Accordingly, thesacrificial layer structure 22 may include the sequentially stacked padoxide layer 14, silicon nitride layer 16, silicon oxide layer 18, andfirst protecting layer 20.

Referring to FIG. 5, the sacrificial layer structure 22 may be partiallyetched to form a first opening 24, i.e., hole, exposing at least aportion of the upper surface of the semiconductor substrate 10 in thefirst impurity region 12. The first opening 24 may be located in aregion where the single crystalline epitaxial layer pattern will beformed, as described below.

Although not depicted in drawings, a plurality of first openings 24 maybe regularly arranged at substantially the same interval. Further, thefirst opening 24 may have a minimum width formed by a photolithographyprocess. The first opening 24 may have a width of about 30 nm to about50 nm.

Referring to FIG. 6, a spacer layer (not shown) may be formed on a sidesurface and a bottom surface of the first opening 24. The spacer layermay have an etching selectivity higher than that of the first protectinglayer 20. That is, during etching of the spacer layer, preventingetching of the first protecting layer 20 may be desirable. Further, thespacer layer may include a material substantially the same as that of alayer beneath the first protecting layer 20, i.e., the silicon oxidelayer 18. This may allow removal of the silicon oxide layer 18 togetherwith the spacer layer. Accordingly, the spacer layer may include siliconoxide.

A space between portions of the spacer layers on opposing sidewalls ofthe first opening 24 may correspond to a pillar width of the channel ofportion in the vertical transistor to be formed later, as describedbelow. Thus, the pillar width of the channel portion in the verticaltransistor may be adjusted by controlling a thickness of the spacerlayer. For example, in order to form a desired pillar width, the spacerlayer may have a thickness substantially the same as a half of a desireddecrease width from the width of the first opening 24.

In order to provide the vertical transistor with a nano-wire structurethat enables a volume inversion in the vertical transistor, the pillarwidth of the channel portion may be about 5 nm to about 30 nm.Preferably, the pillar width of the channel portion is about 10 nm.Thus, when the first opening 24 has a width of about 30 nm and a desiredpillar width is about 10 nm, the spacer layer may have a width of about10 nm.

The spacer layer may then be anisotropically etched to form an innerspacer 26 on the side surface of the first opening 24. The inner spacer26 may have an upper surface lower than the upper surface of thesacrificial layer structure 22. Preferably, the upper surface of theinner spacer 26 is aligned substantially coplanar with that of thesilicon oxide layer 18. Such a configuration may enable a sidewall of acontact portion of the later formed single crystalline epitaxial layerpattern to be protected by the first protecting layer 20. Hereinafter, aportion of the first opening 24 remaining after the inner spacer 26 hasbeen formed is referred to a second opening 28.

The contact portion of the single crystalline epitaxial layer patternmay be formed in a space of the second opening 28 between the uppersurface of the inner spacer 26 and the upper surface of the sacrificiallayer structure 22. Thus, a thickness of the contact portion may beadjusted by controlling an etched thickness of the inner spacer 26.Further, the channel portion of the single crystalline epitaxial layerpattern may be formed in a space of the second opening 28 between theupper surface of the inner spacer 26 and the upper surface of thesemiconductor substrate 10. Therefore, a thickness of the channelportion may be adjusted by controlling the etched thickness of the innerspacer 26. As a result, a doping concentration in the second impurityregion may be readily controlled by adjusting the thickness of thecontact portion.

Referring to FIG. 7, a polysilicon layer (not shown) may be formed onthe sacrificial layer structure 22 and fill the second opening 28. Thepolysilicon layer may be formed by, e.g., a low pressure chemical vapordeposition (LPCVD) process. The LPCVD process may be performed in-situwith a channel doping process.

The polysilicon layer may be planarized by, e.g., a chemical mechanicalpolishing (CMP) process, until the upper surface of the sacrificiallayer structure 22 is exposed to form a polysilicon layer pattern 30.Alternatively, an amorphous silicon layer may be formed in the secondopening 28. The amorphous silicon layer may be planarized to form anamorphous silicon layer pattern.

Referring to FIG. 8, a laser epitaxial growth process may be performedon the semiconductor substrate 10 to convert the polysilicon layerpattern 30 into the single crystalline epitaxial layer pattern 32.

The laser used in the epitaxial growth process may have an energydensity sufficient for completely melting the polysilicon layer pattern30. Particularly, the laser may irradiate the polysilicon layer pattern30 to melt the polysilicon layer pattern 30, thereby converting a solidphase into a liquid phase in the polysilicon layer pattern 30. The phasechange may be generated from an upper surface of the polysilicon layerpattern 30 to the upper surface of the semiconductor substrate 10. Inorder to melt the polysilicon layer pattern 30, the laser may have atemperature of about 1,410° C., corresponding to a melting temperatureof the polysilicon layer pattern 30.

The single crystalline semiconductor substrate 10 may function as a seedfor the liquefied polysilicon layer pattern 30 to convert thecrystalline structure into a single crystalline structure in thepolysilicon layer pattern 30. A laser emitter for irradiating the lasermay include, e.g., a gas laser emitter such as an excimer laser emitter.In order to reduce an irradiation time of the laser, the laser emittermay have a scan function.

During the laser irradiation, the single crystalline semiconductorsubstrate 10 may be heated. The heating of the semiconductor substrate10 may reduce a temperature gradient in the polysilicon layer pattern30. For example, the single crystalline semiconductor substrate 10 maybe heated to a temperature of about 400° C. during the laserirradiation.

As mentioned above, the laser may irradiate the polysilicon layerpattern 30 to convert the crystalline structure into the singlecrystalline structure in the polysilicon layer pattern 30, therebyforming the pillar-shaped single crystalline epitaxial layer pattern 32on the single crystalline semiconductor substrate 10.

The single crystalline epitaxial layer pattern 32 may have a shapevertically protruding from the upper surface of the semiconductorsubstrate 10. The single crystalline epitaxial layer pattern 32 mayserve as an active body.

The single crystalline epitaxial layer pattern 32 may have a channelportion 32 a and a contact portion 32 b. The channel portion 32 a may beformed on the upper surface of the semiconductor substrate 10. Further,the channel portion 32 a may have a first width d1. The channel portion32 a may be used as a channel region of the vertical transistor. Thecontact portion 32 b may be formed on the channel portion 32 a. Thecontact portion 32 b may have a second width d2 greater than the firstwidth d1 of the channel portion 32 a. The contact portion 32 b may be animpurity region of the vertical transistor.

Alternatively, the single crystalline epitaxial layer pattern 32 may beformed by, e.g., a solid phase epitaxial regrowth process, a metalinduced crystallization process using a metal catalyst, etc. That is,the polysilicon layer pattern 30 may be thermally treated using afurnace at a temperature of about 600° C. to about 700° C. to convertthe crystalline structure into the single crystalline structure.

Referring to FIG. 9, a second protecting layer 34 may then be formed onthe single crystalline epitaxial layer pattern 32 and the sacrificiallayer structure 22. Therefore, the upper sidewall and upper surface ofthe single crystalline epitaxial layer pattern 32 may be covered withthe first protecting layer 20 and the second protecting layer 34.

Referring to FIG. 10, the second protecting layer 34, the firstprotecting layer 20, and the silicon oxide layer 18 may be etched toform a stacked structure 36. The stacked structure 36 may have a linearshape covering the single crystalline epitaxial layer pattern 32. Inaddition, the stacked structure 36 may extend in a directionsubstantially the same as an extending direction of a gate electrode tobe formed later, as described below. That is, the first protecting layer20 and the second protecting layer 34 may have a linear extending shapecovering the upper sidewall and the upper surface of the singlecrystalline epitaxial layer pattern 32.

Referring to FIG. 11, the silicon oxide layer 18 and the inner spacer 26in the stacked structure 36 may be removed by, e.g., an isotropicetching process. When the isotropic etching process is completed, thesidewall of the single crystalline epitaxial layer pattern 32 where thechannel region will be formed may be exposed. Portions of the firstprotecting layer 20 and the second protecting layer 34 may still remain.

Referring to FIG. 12, a gate insulating layer 38 may be formed on thesidewall of the single crystalline epitaxial layer pattern 32, e.g., thechannel portion 32 a, and the upper surface of the semiconductorsubstrate 10. The gate insulating layer 38 may be formed by, e.g., athermal oxidation process. The gate insulating layer 38 may not beformed on the contact portion 32 b of the epitaxial layer pattern 32 andthe silicon nitride layer 16. Thus, the gate insulating layer 38 may beformed only on the channel portion 32 a of the epitaxial layer pattern32.

A gate conductive layer 40 may be formed on the gate insulating layer 38and the semiconductor substrate 10 to cover the single crystallineepitaxial layer pattern 32. The gate conductive layer 40 may includepolysilicon formed by, e.g., an LPCVD process. The gate conductive layer40 may be planarized until the upper surface of the second protectinglayer 34 is exposed.

Referring to FIG. 13, the gate conductive layer 40 may then be patternedto form a gate electrode 40 a. The gate electrode 40 a may have a linearshape surrounding the single crystalline epitaxial layer pattern 32. Thegate electrode 40 a may be formed by, e.g., an etching process. Theetching process may use the silicon nitride layer 16 as an etching stoplayer.

As illustrated in FIG. 2, the gate electrode 40 a may surround each ofthe regularly arranged single crystalline epitaxial layer patterns 32.

Impurities may be implanted into the contact portion 32 b of theepitaxial layer pattern 32 to form a second impurity region 42. Thesecond impurity region 42 may be used for any one of the source regionand the drain region of the vertical transistor. In an implementation,prior to forming the second impurity region 42, the silicon nitridelayer 16 may be removed by, e.g., a wet etching process.

Alternatively, the process for forming the second impurity region 42 maybe performed between the process for forming the single crystallineepitaxial layer pattern 32 and the process for forming the gateelectrode 40 a.

According to this embodiment, the vertical transistor having thenano-wire shaped channel region may be manufactured by simple processes.

DRAM Device

FIG. 14 illustrates a cross-sectional view of a DRAM device includingthe vertical transistor of FIG. 1. FIG. 15 illustrates a plan view of aDRAM device including the vertical transistor of FIG. 1.

Here, the DRAM device of FIGS. 14 and 15 of the embodiment may include avertical transistor substantially the same as that illustrated inFIG. 1. Thus, any further illustrations with respect to the verticaltransistor are omitted herein for brevity. Further, a bit line isomitted in FIG. 15.

Referring to FIGS. 14 and 15, a semiconductor substrate 10 may have anactive region 10 b and an isolation region 10 a. The semiconductorsubstrate 10 may include single crystalline silicon. The isolationregion 10 a may be defined by isolation layer patterns formed in anupper surface of the semiconductor substrate 10. The active region 10 bmay have an isolated shape repeatedly arranged. A first impurity region12 may be formed in the upper surface of the semiconductor substrate 10in the active region 10 b.

A pillar-shaped single crystalline epitaxial layer pattern 32 maycontact the active region 10 b. The single crystalline epitaxial layerpattern 32 may be used as an active body. The single crystallineepitaxial layer pattern 32 may protrude vertically from the uppersurface of the semiconductor substrate 10.

The two single crystalline epitaxial layer patterns 32 may be spacedapart from each other in a single isolated active region 10 b. Thesingle crystalline epitaxial layer pattern 32 may have a channel portionhaving a first width and a contact portion on the channel portion havinga second width that may be greater than the first width. The first widthmay be about 5 nm to about 30 nm. Here, the single crystalline epitaxiallayer pattern 32 may have a structure substantially the same as that ofthe single crystalline epitaxial layer pattern of FIGS. 1 to 3.

A gate insulating layer 38 may be formed on a sidewall of the channelregion of the epitaxial layer pattern 32 and the upper surface of thesemiconductor substrate 10. The gate insulating layer 38 may be formedby, e.g., a thermal oxidation process. The gate insulating layer 38 maynot be formed on the contact portion.

A gate electrode 40 a may be formed on the gate insulating layer 38. Thegate electrode 40 a may have a linear shape surrounding the epitaxiallayer pattern 32. Thus, the gate electrode 40 a may be used commonlywith a word line. That is, the gate electrode 40 a may not have anisolated shape. Thus, the linear gate electrode 40 a may be used as theword line without forming a separate word line in contact with the gateelectrode 40 a.

The gate electrode 40 a and the active region 10 b may extend at anangle of no more than about 90° relative to one another. That is, thegate electrode 40 a may be arranged inclined, not substantiallyperpendicular, relative to the active region 10 b.

A second impurity region 42 may be formed in the contact portion of thesingle crystalline epitaxial layer pattern 32. A first insulatinginterlayer 50 may cover the single crystalline epitaxial layer pattern32. The first insulating interlayer 50 may include, e.g., silicon oxide.

A bit line contact 52 may be formed through the first insulatinginterlayer 50. The bit line contact 52 may contact the active region 10b between the single crystalline epitaxial layer patterns 32. A bit line54 may be formed on the bit line contact 52 and the first insulatinginterlayer 50. The bit line 54 may be arranged substantiallyperpendicular to the gate electrode 40 a. Further, the bit line 54 maycontact adjacent bit line contacts 52.

A hard mask pattern 56 may be formed on the bit line 54. A secondinsulating interlayer 58 may cover the bit line 54.

A storage node contact 60 may be formed through the second insulatinginterlayer 58 and the first insulating interlayer 50. The storage nodecontact 60 may contact an upper surface of the single crystallineepitaxial layer pattern 32.

A capacitor 62 may be formed on the storage node contact 60. Thus, thecapacitor 62 may be electrically connected to the single crystallineepitaxial layer pattern 32.

According to the present embodiment, the DRAM device may include thevertical transistor having the nano-wire shaped channel region, so thatthe DRAM device may have a rapid operational speed. Further, the DRAMdevice may occupy only a small area.

Method of Manufacturing a DRAM Device

FIGS. 16 to 20 illustrate cross-sectional views of stages in a method ofmanufacturing the DRAM device of FIG. 14.

Referring to FIG. 16, a shallow trench isolation (STI) process may beperformed on a semiconductor substrate 10 to define an active region andan isolation region 10 b (not illustrated) of the semiconductorsubstrate 10. The active region may have an isolated shape. Further, theactive region may be regularly arranged.

Impurities may be implanted into the semiconductor substrate 10 to forma first impurity region 12. Additionally, a channel doping process maybe performed to control a threshold voltage of a transistor. In animplementation, the process for forming the first impurity region 12 maybe performed prior to forming the active region.

Processes substantially the same as those illustrated with reference toFIGS. 4 to 10 may be performed to form a single crystalline epitaxiallayer pattern 32 on the active region. The single crystalline epitaxiallayer pattern 32 may have a shape vertically extending from an uppersurface of the semiconductor substrate 10.

A sacrificial layer structure may be formed on the semiconductorsubstrate 10. The sacrificial layer structure may have openings exposingthe first impurity region 12. Here, the sacrificial layer structure maycover the entire upper surface of the semiconductor substrate 10. Twoepitaxial layer patterns 32 may be located in the single active region.Thus, the two openings may be located in the single active region.

An inner spacer 26 may be formed on side surfaces of the openings. Theopenings may be filled with the single crystalline epitaxial layerpatterns 32. Each of the epitaxial layer patterns 32 may have a channelportion having a first width and a contact portion on the channelportion having a second width that may be greater than the first width.Thus, the two pillar-shaped single crystalline epitaxial layer patterns32 may be formed in the single isolated active region. The singlecrystalline epitaxial layer pattern 32 may be used as an active body.

The channel portion of the single crystalline epitaxial layer pattern 32may have a width of about 5 nm to about 30 nm. The sacrificial layerstructure may then be patterned to expose a silicon oxide layer 18 ofthe sacrificial layer structure. Here, a pad oxide layer 14 and asilicon nitride layer 16 of the sacrificial layer structure may not beetched. Therefore, the pad oxide layer 14 and the silicon nitride layer16 may remain on the active region and the isolation region 10 b (notillustrated). The single crystalline epitaxial layer pattern 32 may beformed by, e.g., a laser epitaxial growth process.

Referring to FIG. 17, the inner spacer 26 and the silicon oxide layer 18on the sidewall of the single crystalline epitaxial layer pattern 32 maybe removed by, e.g., an isotropic etching process. Here, because theisolation region 10 b (not illustrated) may be covered with the siliconnitride layer 16, isolation layer patterns in the isolation region 10 bmay not be removed.

Referring to FIG. 18, a gate structure may be formed in a spacegenerated by removing the inner spacer 26 and the silicon oxide layer18. A gate insulating layer 38 may be formed on the sidewall of thesingle crystalline epitaxial layer pattern 32. The gate insulating layer38 may be formed by, e.g., a thermal oxidation process. A gate electrode40 a may be formed on the gate insulating layer 38. The gate electrode40 a may have a linear shape surrounding the single crystallineepitaxial layer pattern 32. Here, the gate insulating layer 38 and thegate electrode 40 a may be formed by processes substantially the same asthose illustrated with reference to FIGS. 12 and 13. Because the gateelectrode 40 a may have the linear shape, the gate electrode 40 a may beused commonly with a word line.

The gate electrode 40 a may be arranged at an angle relative to anextending direction of the active region. That is, the gate electrode 40a and the active region may be arranged at an angle relative to oneanother of no more than about 90°. Therefore, cells of the DRAM devicemay be densely arranged, so that the DRAM device may have a high degreeof integration.

Impurities may be implanted into the contact portion of the singlecrystalline epitaxial layer pattern 32 to form a second impurity region42, thereby completing a vertical transistor. The process for formingthe second impurity region 42 may be performed prior to forming the gateelectrode 40 a. That is, the process for forming the second impurityregion 42 may be performed between the process for forming the singlecrystalline epitaxial layer pattern 32 and a process for forming thefirst insulating interlayer 50.

Referring to FIG. 19, the first insulating interlayer 50 may cover thevertical transistor. The first insulating interlayer 50 may be etched toform a contact hole exposing the active region between the singlecrystalline epitaxial layer patterns 32.

A first conductive layer (not shown) may be formed on the firstinsulating interlayer 50 to fill up the contact hole. The firstconductive layer may be used as a bit line contact and a bit line. Thefirst conductive layer may include no less than two layered structures.A hard mask pattern 56 may be formed on the first conductive layer. Thehard mask pattern 56 may have a linear shape extending in a directionsubstantially perpendicular to the extending direction of the gateelectrode 40 a. The first conductive layer may be etched using the hardmask pattern 56 as an etch mask to form a bit line contact 52 and a bitline 54. Thus, the bit line contact 52 and the bit line 54 may be formedone body. Alternatively, after forming the bit line contact 52, the bitline 54 may be separately formed.

Referring to FIG. 20, a second insulating interlayer 58 may cover thebit line 54. The second insulating interlayer 58, the first insulatinginterlayer 50, and the second protecting layer 34 may be etched to formcontact holes exposing the upper surface of the single crystallineepitaxial layer pattern 32. The contact holes may be filled with aconductive material to form storage node contacts 60.

The storage node contact 60 may not extend to the upper surface of thesemiconductor substrate 10 in the active region. The storage nodecontact 60 may contact the upper surface of the single crystallineepitaxial layer pattern 32. Therefore, it may not be required to providea region of the active region where the storage node contact 60 may beformed. As a result, the active region may occupy only a small area ofthe semiconductor substrate 10.

Further, the storage node contact 60 may have a relatively low height.The upper surface of the single crystalline epitaxial layer pattern 32,on which the storage node contact 60 may be formed, may have a largeupper surface. Thus, the storage node contact 60 may be easily formed.

A capacitor 62 may be formed on the storage node contact 60. Thecapacitor 62 may have, e.g., a cylindrical shape, a stack shape, etc.

According to this embodiment, the DRAM device may include the verticaltransistor having a narrow pillar width. Thus, the vertical transistormay have a rapid operational speed and occupy a small area. As a result,the DRAM device may have a high degree of integration and improvedoperational characteristics.

Memory System

FIG. 21 illustrates a block diagram of a memory system in accordancewith an embodiment.

Referring to FIG. 21, a memory system of an embodiment may include amemory controller 520 and a memory 510. The memory 510 may include thevertical transistor of an embodiment. That is, the memory 510 may beused as the DRAM device of an embodiment. The memory controller 520 mayinput a signal into the memory 510 to control operations of the memory510. The signal may include, e.g., a command signal, an address signal,an input/output signal, etc. The memory controller 520 may control datain the DRAM device in accordance with the signal.

Host System

FIG. 22 illustrates a block diagram of a host system in accordance withan embodiment.

Referring to FIG. 22, a host system 700 of an embodiment may beconnected to a memory 510. The memory 510 may include the verticaltransistor of an embodiment. The host system 700 may include anelectronic device, e.g., a personal computer, a camera, a mobile device,a game device, a communication device, etc. The host system 700 mayapply a signal, which may be used for control and operate the memory510, to the memory 510.

Portable Device

FIG. 23 illustrates a block diagram of a portable device in accordancewith an embodiment.

Referring to FIG. 23, a portable device 600 of an embodiment mayinclude, e.g., an MP3 player, a video player, etc. The portable device600 may include a memory 510 and a memory controller 520. The memory 510may include a recessed channel array transistor of an embodiment. Thetransistor may be formed in a peripheral region of the memory 510. Theportable device 600 may also include, e.g., an encorder/decorder 610, adisplay 620, and an interface 670. Data may be inputted/outputtedinto/from the memory 510 through the memory controller 520 by theencorder/decorder 620.

Computer system

FIG. 24 illustrates a block diagram of a computer system in accordancewith an embodiment.

Referring to FIG. 24, the memory 510 may be connected with a centralprocessing unit (CPU) 510 of a computer system 800. The computer system800 may include, e.g., a personal computer, a personal data assistantdevice, etc. The memory 510 may be connected to the CPU 810 directly orindirectly via a bus. The memory 510 may include the recessed channelarray transistor of an embodiment. The transistor may be formed in aperipheral region of the memory 510. Although not depicted in drawings,other elements may be included in the computer system 800.

General Commentary

Vertical transistors of an embodiment may be used in varioussemiconductor devices that include transistors. Particularly, verticaltransistors of an embodiment may be used in a DRAM device and electronicdevices including DRAM devices.

According to some embodiments, the vertical semiconductor device mayhave a nano-wire shaped channel region. Thus, a desirable volumeinversion may be generated during operation of the verticalsemiconductor device, so that the channel region may have a highconductivity. Further, the semiconductor device having the nano-wireshaped channel region may be formed by simple processes, so that a costfor manufacturing the semiconductor device may be reduced.

Exemplary embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation.Accordingly, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made without departingfrom the spirit and scope of the present invention as set forth in thefollowing claims.

What is claimed is:
 1. A method of manufacturing a verticalsemiconductor device, the method comprising: implanting impurities intoa single crystalline substrate to form a first impurity region; forminga sacrificial layer structure on an upper surface of the substrate, suchthat the sacrificial layer structure has holes exposing the firstimpurity region on the upper surface of the single crystallinesubstrate; forming inner spacers on side surfaces of the holes;vertically forming single crystalline active bodies in the holes on theupper surface of the single crystalline substrate, such that each of thesingle crystalline active bodies has a first active portion on thesubstrate and a second active portion on the first active portion andsuch that the first active portion has a first width smaller than asecond width of the second active portion; forming a gate insulatinglayer on a sidewall of the first active portion and the upper surface ofthe substrate; forming a gate electrode on the gate insulating layer,such that the gate electrode has a linear shape surrounding the activebodies; and implanting impurities into the second active portion to forma second impurity region.
 2. The method as claimed in claim 1, whereinforming the sacrificial layer structure includes: forming a sacrificiallayer on the substrate; forming a first protecting layer on thesacrificial layer; and etching the sacrificial layer and the firstprotecting layer to form the sacrificial layer structure having theholes.
 3. The method as claimed in claim 2, wherein forming thesacrificial layer includes: forming a pad oxide layer on the substrate;forming a silicon nitride layer on the pad oxide layer; and forming asilicon oxide layer on the silicon nitride layer.
 4. The method asclaimed in claim 2, further including forming a second protecting layeron the sacrificial layer structure to cover the active bodies.
 5. Themethod as claimed in claim 2, further including: patterning thesacrificial layer structure to expose the sacrificial layer; andremoving the sacrificial layer and inner spacers to expose the sidewallof the first active portion.
 6. The method as claimed in claim 5,wherein the gate insulating layer is formed on the exposed sidewall ofthe first active portion.
 7. The method as claimed in claim 1, whereinthe inner spacer has an upper surface lower than that of the sacrificiallayer structure.
 8. The method as claimed in claim 7, wherein a distancebetween the upper surface of the inner spacer and the upper surface ofthe sacrificial layer structure is substantially the same as a length ofthe second active portion.
 9. The method as claimed in claim 1, whereina width between the inner spacers in the hole is about 5 nm to about 30nm.
 10. The method as claimed in claim 1, wherein forming the activebodies includes: filling an opening between the inner spacers with apolysilicon layer pattern; and thermally treating the polysilicon layerpattern using a laser to form the active bodies.
 11. The method asclaimed in claim 1, wherein forming the gate insulating layer and thegate electrode includes: oxidizing surfaces of the first active portionand the substrate to form the gate insulating layer; forming aconductive layer on the substrate to cover the gate insulating layer;and patterning the conductive layer to form the linear gate electrode.12. A method of manufacturing a DRAM device, the method comprising:implanting impurities in an upper surface of a single crystallinesubstrate to form a first impurity region; forming a sacrificial layerstructure on the upper surface of the substrate, such that thesacrificial layer structure has holes exposing the first impurity regionin the upper surface of the single crystalline substrate; forming innerspacers on side surfaces of the holes; vertically forming singlecrystalline active bodies in the holes on the upper surface of thesingle crystalline substrate, such that each of the single crystallineactive bodies has a first active portion on the substrate and a secondactive portion on the first active portion and such that the firstactive portion has a first width smaller than a second width of thesecond active portion; forming a gate insulating layer on a sidewall ofthe first active portion and the upper surface of the substrate; forminga gate electrode on the gate insulating layer, such that the gateelectrode has a linear shape surrounding the active bodies; implantingimpurities into the second active portion to form a second impurityregion; electrically connecting a bit line structure to the firstimpurity region; and electrically connecting a capacitor to the secondimpurity region.
 13. The method as claimed in claim 12, wherein formingthe active bodies includes: filling an opening between the inner spacerswith a polysilicon layer pattern; and thermally treating the polysiliconlayer pattern using a laser to form the active bodies.
 14. The method asclaimed in claim 3, wherein an upper surface of the silicon oxide layeris substantially aligned with an upper surface of the single crystallineactive bodies.
 15. The method as claimed in claim 5, wherein a portionof the first protecting layer remains after the removing of thesacrificial layer and inner spacers.
 16. The method as claimed in claim1, wherein a width of the active bodies is adjusted by controlling athickness of the inner spacers.
 17. The method as claimed in claim 1,wherein the gate electrode has an upper surface lower than an uppersurface of the active bodies.
 18. The method as claimed in claim 12,further including forming a storage node contact on an upper surface ofeach of the active bodies.